1. Field of the Invention
The present invention relates to novel antitumor antibiotics, process for their fermentative production, and the producing microorganism per se.
2. Background Art
U.S. Pat. No. 4,360,458 issued to Koshiyama et al on Nov. 23, 1982 discloses an antitumor complex designated BBM-928 (now called luzopeptin) produced by Actinomadura luzonensis ATCC 31491. U.S. Pat. No. 4,451,456 issued to Koshiyama et al on May 29, 1984 and UK Published Application No. 2,134,119, published Aug. 4, 1984 disclose the structures of antibiotics BBM-928A, B, C, D and E2 as follows:
__________________________________________________________________________ ##STR2## Component R.sub.1 R.sub.2 __________________________________________________________________________ A acetoxy acetoxy B acetoxy hydroxy C hydroxy hydroxy D acetoxy propionyloxy E2 hydrogen hydrogen __________________________________________________________________________
U.S. Pat. No. 4,582,639 issued to Matson et al on Apr. 15, 1986 discloses the antibiotic sandramycin produced by Nocardioides sp. strain C49,009, and having the structural formula ##STR3##
Microbially derived quinoxaline antibiotics may be exemplified by echinomycin whose structure is reported in Dell et al, "Structure Revision of the Antibiotic Echinomycin," Journal of the American Chemical Society, 1975, 97:2497-2502 as the following: ##STR4##
Compounds of the present invention are distinguished over the afore-mentioned depsipeptide antibiotics by the presence of a quinoxaline nucleus and a tetrahydropyridazine moiety.